Known from the publication DE 103 05 241 A1 is a 6-speed or 7-speed dual clutch transmission. The dual clutch transmission comprises two clutches, each being connected with their inputs to the drive shaft and with an output to one of the two transmission input shafts. The two transmission input shafts are coaxially positioned with respect to each other. In addition, two countershafts are positioned to be axially parallel to the transmission input shafts, their idle gears mesh with the fixed gear wheels of the transmission input shafts. Furthermore, coupling devices that are axially movable, are connected in a rotationally fixed manner to the countershaft to shift the respective gear wheels. Each selected ratio is transferred by the drive gear wheels to a differential transmission. To achieve the desired gear ratio steps in this known dual clutch transmission, a vast number of gear wheel planes are required, so that a significant amount of installation space is needed.
In addition, a spur gear change speed transmission is known from the publication DE 38 22 330 A1. The spur gear change speed transmission comprises a dual clutch, that is shiftable under power, and where one part is connected with a drive shaft and the other part with a hollow drive shaft that is positioned rotatably on the drive shaft. For certain gear ratios, the drive shaft can be coupled with the hollow drive shaft through a shifting device.
Known from the publication DE 10 2004 001 961 A1 is a power transmission with two clutches, each of which are assigned to a partial transmission. The transmission input shafts of the two partial transmissions are positioned coaxially with respect to each other and mesh, via fixed gear wheels, with idle gears of the designated countershaft. The respective idle gears of the countershafts can be connected, in a rotationally fixed manner, with the respective countershaft by designated shifting devices. The particular idle wheels of the countershaft can be connected in a rotationally fixed manner through the assigned shifting devices with the associated countershaft. A 7-gear transmission, among other things, is known through this publication in which an additional shift element is provided to connect the two transmissions input shafts to establish an additional transmission stage. The 7-gear transmission requires in this embodiment at least six gear wheel planes in the two partial transmissions, to achieve the transmission stages. This causes an unwanted extension of the construction length in axial direction. It is therefore significantly limiting the use in a motor vehicle.